VPN's and equivalents(Tor) don't truly offer any security advantage (unless specially designed to do so) but they do offer a privacy advanatge to anyone wishing to browse without their ISP, the sites they visit or others being able to see who they are.
For question 1. In general you don't need to worry about people seeing your IP address, and only large companies or national governments can use it to find your true identitity. It is also possible (though not always true)that your ip adress varies every few hours, so only governments or large companies would be able to use it to wor out your browsing from day to day(as they can access records of who had what Ip adress at what time). Hiding an IP adress doesn't usually help security, but if you desire privacy it can be wise.
For question2. Usually NO. a properly working VPN (or other anonymity solution) forwards the content of apegs you visit to you along what one might call an "encrypted pipe", unless the VPN is run by distrustworhty people wanting to spy on user's actions, then it neither sees nor alters any of the content between the pages you visit and your machine, it just encrypts them, passes them around a bit to give you anonymity and then lets your computer do the de-cryption, Tor uses the same principle but with more steps between you and the sites you visit. Cookies will probably still be placed on your machine, though thye migth be made invalid as soon as your browsing session ends, cokies can be wiped easily by the user regardles of whether they browse normally or anonymously.
There are a few reasons other than anonymity that someone might use a VPN or Tor like system:
1.Anonymity, they wish to browse without being recorded by ISP's, governments, others. Just because you want to be anonymous doesn't mean you have something to hide.
2.Avoiding internet blocks, because thye send traffic from your computer to the websites you visit (and vice versa) along an "encrypted pipe" VPN services let a user bypass geographical or other restrictions on some web pages. If a site refuses access to users in country A but lets people in country B visit, then a user in country A could use a VPN to appear to the site as if he was from country B because if his VPN "came out" of it's "pipe" in country B then the sites the user visits will see him to have a country B IP adress. Similar principles apply if: the country a user is in, the ISP a user is on, or the network a user is on, are blocking particular sites because the network/ISp/nation doing the blocking will just see a user has an encrypted link to a VPN and not know where the VPN is "tunnelling" to.
3.Wi-fi, at many wifi hotspots there is a risk of snoopers being able to see the sites people are visiting, and the contents of the pages if the pages are http (rather than https). A VPN gives the user an encrypted tunnel from his machine, through the wi-fi hotspot network and o to the widr web, all that a snooper in the wi fi network could see would be a user having an encrypted https connection to a VPN, he wouldn't be able to find the actual pages thye were visiting, much less see the content on them or the data a user was typing in. This is the one application where a VPN would be considered as a "security" measure.
Edited by rp88, 21 March 2015 - 01:59 PM.
Back on this site, for a while anyway, been so busy the last year.
My systems:2 laptops, intel i3 processors, windows 8.1 installed on the hard-drive and linux mint 17.3 MATE installed to USB